Electrophysiology and glucose transport of human peritoneal mesothelial cells: Implications for peritoneal dialysis

Objective:To elucidate ionic and glucose transport across human peritoneal mesothelium, we utilized an Ussing chamber setup and studied the electrophy siological characteristics and tissue permeabilities of human peritoneal me sothelial cells (HPMC) to L- and D-glucose. Methods: Human mesothelial cells were grown on polyester filters (snapwell; Costar, Cambridge, MA, U.S.A.) that, upon confluence, were fitted into Uss ing chambers. Transmesothelial resistance and resting potential were determ ined using electrophysiological techniques. Radiolabeled glucose was added to one side of the chamber and the permeabilities determined by serial samp ling in the receptive compartment. Results:The transmesothelial potential and resistance were 0.54 +/- 0.07 mV (apical positive) and 20.4 +/- 3.2 Omega .cm(2) respectively (mean +/- SEM , n = 36). The course of overall transfer of D- and L-glucose was examined using L-glucose as a positive diffusion-plus-leak marker. The permeabilitie s of HPMC to D-glucose were 3.00 +/- 0.26 cm/ sec (apical-to-basolateral) a nd 3.25 +/- 0.27 cm/sec (basolateral-to-apical) [n = 6 experiments, p = not significant (NS)], which were not different from those of L-glucose: 3.00 +/- 0.30 cm/sec (apical-to-basolateral) and 2.71 +/- 0.24 (basolateral-to-a pical) (n = 6 experiments, p = NS). Conclusions:The transepithelial resistance of HPMC is low and the ionic gra dient, although it exists, is small and inconsequential. Passive paracellul ar flow accounts for the majority of transmesothelial glucose transport. Th e existence of a large paracellular shunt precludes the mesothelial membran e as a clinically relevant osmotic barrier.